<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

    <g transfrom="skewx(20)">
        <switch>
            <!-- 选择一个子元素 -->
            <foreignObject x="25%" y="25%" width="10em" height="50%" requiredFeatures="www.baidu.com">
                <body xmlns="http://www.w3.org/1999/xhtml">
                    <p>this is an HTML</p>
                </body>  
            </foreignObject>
            <text x="10em" y="25%" dy="1em">
                this is ......
            </text>
        </switch> 
    </g>

    <br>
    
    switch元素会告诉svg阅读器只有在元素的requiredFeatures、requiredExtensions以及systemLanguage属性求值为true或者缺失时，才绘制第一个直接子元素（以及所有子节点）
</html>